Question

A needle and a knife belong to the same group because:

• A. they are transparent
• B. they are hard and magnetic
• C. they float on water
• D. they are poor conductors of heat

Answer 1

The correct option is B they are hard and magnetic

As we know that a needle and a knife both are made up of metals.

Metals are not transparent, their density is higher than water so they sink easily in water and metals are a good conductor of heat and electricity.

But metals are hard (except some exception like $Hg,Na$ etc) and they are magnetic.